840691 has 4 divisors (see below), whose sum is σ = 855000. Its totient is φ = 826384.

The previous prime is 840683. The next prime is 840703. The reversal of 840691 is 196048.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 840691 - 2³ = 840683 is a prime.

It is a super-2 number, since 2×840691² = 1413522714962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (840601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7066 + ... + 7183.

It is an arithmetic number, because the mean of its divisors is an integer number (213750).

2⁸⁴⁰⁶⁹¹ is an apocalyptic number.

840691 is a deficient number, since it is larger than the sum of its proper divisors (14309).

840691 is a wasteful number, since it uses less digits than its factorization.

840691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14308.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 840691 is about 916.8920329025. The cubic root of 840691 is about 94.3797449480.

The spelling of 840691 in words is "eight hundred forty thousand, six hundred ninety-one".